1. Field of the Invention
The present invention relates to a ball screw, and more particularly to a ball screw with a dust-proof and lubricating device.
2. Description of the Prior Art
FIG. 1 shows a first type of conventional dust-proof and lubricating device for a ball screw, wherein the nut 11 is formed with a blind hole 111 which is parallel to the axis 121 of the screw 12, then a plurality of radial oil-feeding holes 113 are formed to communicate the blind hole 111 with the helical groove 112 of the nut 11 or the helical groove 122 of the screw 12, so that lubricant oil can be fed into the blind hole 111 and flows to the helical groove 112 of the nut 11 via the radial oil-feeding holes 113. However, when the ball screw is disposed in a vertical position, lubricant oil will be unable to flow through the radial oil-feeding holes 113 into the helical groove 112 of the nut 11 due to the influence of gravity.
FIG. 2 shows a second type of conventional dust-proof and lubricating device for a ball screw, wherein a solid lubricant 15 is disposed at both ends of the nut 14, and then covered with a dust-proof member 16, so that the interior of the ball screw can be lubricated by the solid lubricant 15 automatically. The problem is that the solid lubricant 15 needs to be replaced when it is used up, which is inconvenient for the user.
FIG. 3 shows a third type of conventional dust-proof and lubricating device for a ball screw, wherein an oil-storage device 18 is disposed at one end of the nut 171 to define an oil-storage space 181 between the outer surface of the screw 172 and the oil-storage device 18. Then, an oil tank 191 is disposed outside the ball screw, and a pump 192 is used to draw oil from the oil tank 191 to the oil-storage device 18. However, arranging the oil-storage device 18 at one end of the nut 171 will add length to the nut 171 while reducing the travel length of the nut.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.